Resetting timer



NOV. 26, 1940. c 2,223,207

RESETTING TIMER Filed Feb. 14, 1940 Inventor: Charles A. Ellis,

His Attorney.

Patented Nov. 26, 1940 UNITED STATES PATENT OFFICE RESETTING TIMER ration of Maine Application February 14, 1940, Serial No. 318,867

4 Claims.

My invention relates to apparatus for timing relatively short intervals to facilitate the accurate timing of processes and the like. Its object is to provide a simple, low cost timer which may quickly be reset for a repetition of the timing operation. The timing interval is easily adlustable and the time interval for which set, as well as the time already expired or remaining in any time interval, is indicated. The device may be adapted to control a switching device and to give an audible alarm at the expiration of the interval being timed.

The features of my invention which are believed to be novel and patentable will be pointed out in the claims appended hereto. For a better understanding of my invention reference is made, in the following description, to the accompanying drawing, in which Fig. 1 represents an exploded perspective view of the operating parts of the timer; Fig. 2 represents a face view of the timer; and Fig. 3 a cross-section of a resetting clutch used in the timer.

The timing and operating motor for the device is represented in Fig. 1 by an electric motor having a stator I0, field coil Ii and enclosed rotor and gear casing l2. This motor unit may be and preferably is a self-starting synchronous motor unit of the type commonly employed in electric clocks. The gearing in casing I2 is for o the purpose of reducing the speed and increasing the available torque of the small input, high speed motor. Further speed reduction may be had by the external gears, I3 to I8 inclusive, some of which perform additional purposes in the opera- 5 tion and resetting of the timer. Gears l6 and Il form parts of a normally engaged clutch shown in cross-section in Fig. 3 used for resetting purposes.

It is seen that the drive through the clutch is to a timer member including the shaft is on which gear I8 is located and the direction of rotation of the gears when driven by the motor in a timing operation is indicated by the arrows on certain of the gears. Gear wheel i8 is provided with a zero stop shown as an uncut portion 20 in its toothed periphery. The zero position of this gear and of the shaft I9 is determined by the stop 20 when it rests against the near surface of gear ll, as viewed in Fig. 1. The details of such stop may, of course, be modified, but the arrangement illustrated employs no parts other than the gears themselves. When gear l8 and shaft iii are advanced from the zero stop position in a clockwise direction by the motor, a spring 2| is wound up. This spring has one end fastened to shaft l9- as by the collar 22 and its other end fastened to a stationary part which may comprise the bearing plate 23. The spring is under some initial tension when the parts are in the zero stop position. The purpose of this spring is to return the 5 timer member parts comprising shaft l9, gear l8 and gear ll to a zero position when the clutch between gears l6 and I1 is released, and the clutch may be released by pressing towards the rear on the thumb nut 24 on a shaft 25 extending forward from the center axis of the clutch.

An indicating pointer 26 is also secured to shaft I9 and comprises a. part of the timer member. This pointer moves over a time dial 2! (see Fig. 2) when shaft l9 rotates and indicates zero on the time dial when the parts are in the zero stop position.

A time setting member including a hollow shaft 28 carrying a gear 29 and a time setting pointer 30, which also indicates on dial 21, has a bearing on and is coaxial with shaft i9 between gear l8 and pointer 26. The gear 29 has a driving lug 3| extending to the rear and arranged to cooperate with a driving lug 32 extending from the front of gear I8, such that gear 29 and pointer 30 may be driven in a clockwise direction by the timer motor when lug 32 is advanced into contact with lug 3|. When gear I3 is in its zero position and the lugs 3| and 32 are in driving contact, lug 3| being ahead or clockwise with respect to lug 32, the pointer 26 will indicate zero and pointer 30 approximately zero on dial 2].

To set the timer for a timing interval the gear 29 and the parts attached thereto are turned in a clockwise direction until pointer 30 indicates the desired timing interval on dial 21. Thus in Fig. 1 the pointer 30 is set to dial reading eighteen. Such setting is accomplished through a worm gear 33 on a rotary spindle 34 provided with a knurled thumb nut 35. It is seen that worm 33 meshes with gear 29 so that pointer 30 may be accurately set by rotation of the thumb nut 35. Spindle shaft 34 is extended downward and is coupled to a movable resilient switch blade 36, having upper and lower contacts cooperating with rela- 45 tively stationary contacts 31 and 38. These contacts are supported at one end and insulated from each other by a suitable supporting and insulating block structure 39.

Spindle shaft 34 has a limited endwise move- 50 ment but is normally held in the position shown in Fig. 1 by switch blade 36 and a light compression spring 40 which surrounds shaft 34 between a collar formed by the upper end of worm gear 33 and a stationary plate ll through 55 which the shaft 34 extends. Shaft 34 is resisted from further downward movement by switch blade 36 which is shown resting on lower contact member 38 holding these contacts closed. The spring 40 adds its force to that of gravity in normally maintaining the shaft 34 in the endwise position shown. The weight of the shaft alone might be depended upon for this purpose if the device was always used in the position shown, but I prefer to include the spring 40 since then the force for holding contacts 36 and 38 closed is positive and independent of the oriented position in which the device might be used.

It is seen now, that when lug 32 is driven by the timer motor in'a clockwise direction from its zero position, it will reach lug 3| in a time interval indicated by the setting of pointer 30 on dial 2'! and. then gear 29 will be driven in a clockwise direction through this lost motion driving connection to the extent necessary to raise shaft 34 a slight amount through the worm 33 and move switch blade 36 from the lower contact 33 to the upper contact 31, thereby performing a. switching operation at the end of the time interval. The dial may be graduated in seconds or minutes or some other selected time units. This graduation will, of course, depend upon the speed of the motor and the gear reduction to shaft is and such gear reduction will be selected to give the time graduations desired. For the purpose of convenience in the explanation, it will be assumed that the dial graduations represent minutes and hence the pointer 26 will be advanced from one graduation to the next in one minute.

The details of the switch and its circuit connections may obviously be varied to produce a wide variety of circuit controlling results. However, it will be seen that circuit connections for stopping the timing motor or for giving a signal at the end of the time interval, or both, as described below should generally be included because of their convenience.

42 represents a suitable source of alternating current supply for the synchronous timer motor II and the motor is connected thereto through switch contacts 36 and 36. Also, an electric signal of any suitable type, but indicated as a bell 43, is connected to source 42 through contacts 33, 36 and 31 in series, and for this arrangement central contact 36, when moved upward, will be arranged to make contact with 31 before it breaks contact with 38. With such an arrangement the normally closed switch will be opened and the timer motor will be stopped at the end of the time interval and a short warning signal will be given just before the motor stops.

A suitable construction for the clutch between gears i6 and i1 is shown in cross-section in Fig. 3. In Fig. 3, 44 is a shaft on which the clutch parts are mounted and this shaft is free to turn in suitable bearing plates at its ends. An axial hole is drilled in shaft 44 from its front end and the push rod 23 is inserted in this hole.- A pin 45 keeps push rod 26, shaft 44 and gear l6 in driving relation and this pin also holds the push rod in place. Gear l6 has a hub part 46 which is free to slide on shaft 44 and which extends loosely in a cavity in the adjacent face of gear H. A collar 41 is fastened to shaft 44 on the opposite side of gear l1, and friction washers 43, which may be made of cork, are provided between the collar 41 and gear I! and between gear I! and the hub 46 of gear i6. A spring 48 is compressed between the hub of gear I6 and a collar 50 secured to shaft 44, and this spring presses the hub of gear l6 into the cavity of gear I! to hold gear ll tightly between the friction washers so that the entire unit rotates and transmits motion between gears l6 and I1. It is desirable to have shaft 44 rotate because it eliminates friction between rotating parts which would otherwise exist due to the compression of spring 43. As arranged, this compression-is between parts which rotate together as a unit.

To release the clutch, pressure is applied to thumb piece 24 to move gear l6 and its hub slightly away from gear l1. Gear H, which has a bearing fitted on shaft 44, is now free to turn on shaft 44 audit is driven to a zero position with gear l8 by spring 2|. It is thus seen that pushing in on thumb piece 24 results in the setting of shaft I9, pointer 26, and the other parts connected thereto to a zero position from any other position, and this resetting operation is performed very quickly. Release of push button 24 immediately reengages the clutch and results in the advance of pointer 26, lug 32, etc. if the timer motor is in operation.

It will be appreciated that where the switch at 36 is operated at the end of the time interval, the gear 23 and hence the pointer 30 will be advanced slightly in order to lift shaft 34 enough to operate the switch. For this reason the pointers 30 and 26 should not coincide exactly when both are in zero positions, but with the lugs 32 in driving engagement with lug 3| the pointer 26 should be exactly on zero and pointer 36 should be in advance thereof by the amount which it is moved in operating the switch at 36.

This does not involve a special setting of pointer 30 for a given time interval. Pointer 30 is set to the exact point on scale 21 for which timing is desired. Thus in Fig. 1 the device is set for 18 minutes. -The pointer 26 will move from its zero position to the position of pointer 30 in exactly 18 minutes and will at'all times indicate the time elapsed and the time remaining in the selected time interval. Thus in the illustration, Fig. 1, 6 minutes have elapsed and 11 minutes remain in the 18 minute time interval before switch 36 will be operated. When pointer 26 reaches the position of pointerv 36 at the end of the time interval, pointer 30 will be advanced the slight amount necessary for the operation of switch 36 and pointer 26 will stop when it indicates the position just previously indicated by pointer 30.

This exact timing interval may now be repeated without any resetting other than that resulting from pushing in on button 24. When button 24 is pushed, pointer 26 snaps back to a zero position and spring 40 returns pointer 30 to its original set position and returns switch 36 to the position shown to restart the motor and another timing operation. It will also be evident that at any time, during a timing operation when pointer 26 is being advanced, the time setting of pointer 30 may be changed in either direction by simply turning thumb nut 36.

The timing interval may be stopped and restarted before pointer 26 reaches pointer 36 by simply pushing button 24. This is advantageous for obtaining timing intervals longer than is provided for. on scale 21. Let us assume for example, thata timing interval of 70 minutes is desired. Pointer 36 may be set for a 40 minute interval and when the pointer 26 first reaches 30 on scale 21, button 24 is pushed and immediately released. This returns pointer 26 to zero and its starts a second advance. This simply adds 30 minutes to the timing and at the termination of minutes, switch 36 will be operated to stop the motor and sound the alarm. In such use of the device, the pushing-in of button 24 does not open the motor circuit or disturb the position of switch 36. Hence any relay control operation that may be desired by operation of switch 36 at the end of the 70 minute interval is not interfered with.

The device may also be used to obtain time out periods or intervals during a timing operation. This stop watch" use of the device is accomplished by simply lifting up on button 35 for the desired time out period or periods This opens the motor circuit and stops the motor during the time button 35 is held up. When button 35 is released, the timing operation is continued until it is stopped in the usual way.

It may be noted that at the end of a time interval, all circuits are opened and are not reclosed until button 24 is pushed. Hence the user may set the device in operation for timing a process and leave it to terminate the process without further attention. At 5 I and 52 I have indicated relays controlled through the switch device at 36. Relay 5| will be energized during the timing interval the same as the timer motor except for any time out periods that may be introduced by lifting of button 35. Relay 52 will be momentarily energized at the end of the time interval with signal'l3. The duration of operation of the signal 43 and relay 52 can be adjusted slightly by the relative spacing of the contact members 36, 31 and 38. Obviously circuit connection and switching arrangements for a wide variety of results may be provided for.

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention together with the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. A timer comprising an electric timer motor, a timer shaft, a speed-reducing gear train through which said shaft may be driven by said motor, a timer pointer on said shaft, a graduated time dial on which said pointer indicates, a normally engaged clutch in said gear train, a spring wound by said motor through said clutch when the motor is in operation and the clutch engaged, manual means for disengaging said clutch, said spring serving to return said timer shaft and pointer to a zero time indicating position when said clutch is disengaged, a time setting shaft coaxial with said timer shaft, a time setting pointer on said time setting shaft also indicating on said dial. manual means for rotating said time setting shaft and pointer to a desired time setting position, driving lugs rotated with said two shafts positioned to interfere when and only when said two pointers give substantially the same indication on said dial, said interference causing the time setting shaft to be driven by said timer shaft when the latter is being driven by said motor, and a normally closed energizing switch for said motor which is opened in response to rotation of said time setting shaft when so driven.

2. A timer comprising an electric timer motor, a timer shaft, a speed reducing gear train including a normally engaged clutch through which said timer shaft is driven by said motor, a spring wound by said motor through said clutch when the motor is in operation and the clutch engaged, manual means for releasing said clutch, said spring serving to return said timer shaft to an initial zero time position when said clutch is released, a gear wheel having a bearing on said timer shaft, a graduated time dial, a timer pointer rotated with said timer shaft and a time setting pointer rotated with said gear wheel, both indicating on said time dial, a time setting spindle having a worm meshing with said gear through which said time setting pointer may be set to a desired position on said dial, said time setting spindle having limited endwise movement, resilient means for resisting such endwise movement and normally retaining said time setting spindle in a fixed endwise position, a' lost motion driving connection through which said gear wheel may be driven by said timer shaft but effective for such purpose only when said two pointers produce substantially the same indication on said dial, and a normally closed switch through which said motor is energized opened by endwise movement of said time setting spindle when it is moved endwise through said worm and gear when the latter is driven through said lost motion driving connection.

3. In a timer, a time setting and switch operating spindle supported for rotational movement and limited endwise movement, a worm thereon, a gear wheel in mesh with said worm, resilient means for resisting endwise movement of said spindle, a switch mechanically coupled to said spindle and operated by endwise movement thereof, a time setting pointer rotatively positioned with said gear wheel and so positioned for time setting purposes by rotation of said spindle, manual means for turning said spindle to set said pointer and for moving the shaft endwise to operate said switch, an electric timer motor energized through said switch for operating said timer, and means driven by said motor for rotating said gear and moving said spindle endwise through said worm to operate said switch at the end of the time interval for which said gear is positioned.

4. A timer comprising an electric timer motor, a timer shaft, a normally engaged manually releasable clutch through which said shaft may be driven in one direction, a spring wound by said motor for rotating said shaft in the opposite direction to a predetermined position when said clutch is released, a dial, a pointer on said shaft indicating on said dial, said dial being graduated in time units corresponding to the time movement of said pointer when said shaft is rotated by said motor from said predetermined position, a time setting pointer indicating on said dial and manually adjustable with respect thereto to indicate a desired time setting of said timer, a normally closed switch through which said motor is energized, means for operating said switch having a part driven by said timer motor and a part adjustable with said time setting pointer effective to automatically operate said switch when said timer motor has advanced the timer pointer to the position indicated by said time setting pointer, said time setting pointer being manually adjustable for shorter or longer timer operating periods during the advance of said timer pointer, and manual means for operating said switch during the advance of said timer pointer to suspend the timing operation.

CHARLES A. ELLIS. 

